Evidence of Season-Dependency in Vegetation Effects on Macrofauna in Temperate Seagrass Meadows (Baltic Sea)

Abstract

Seagrasses and associated macrophytes are important components of coastal systems as ecosystem engineers, habitat formers, and providers of food and shelter for other organisms. The positive impacts of seagrass vegetation on zoobenthic abundance and diversity (as compared to bare sands) are well documented, but only in surveys performed in summer, which is the season of maximum canopy development. Here we present the results of the first study of the relationship between the seasonal variability of seagrass vegetation and persistence and magnitude of contrasts in faunal communities between vegetated and bare sediments. The composition, abundance, biomass, and diversity of macrozoobenthos in both habitats were compared five times throughout the year in temperate eelgrass meadows in the southern Baltic Sea. Significant positive effects of macrophyte cover on invertebrate density and biomass were recorded only in June, July, and October when the seagrass canopy was relatively well developed. The effects of vegetation cover on faunal species richness, diversity, and composition persisted throughout the year, but the magnitude of these effects varied seasonally and followed changes in macrophyte biomass. The strongest effects were observed in July and coincided with maximums in seagrass biomass and the diversity and biomass of other macrophytes. These observations indicate that in temperate, clearly seasonal systems the assessment of macrophyte impact cannot be based solely on observations performed in just one season, especially when that season is the one in which macrophyte growth is at its maximum. The widely held belief that macrophyte cover strongly influences benthic fauna in marine coastal habitats, which is based on summer surveys, should be revisited and complemented with information obtained in other seasons.

Habitat structure influences the seasonality of nekton in seagrass

“…While we summarize these published studies in terms of habitat-specific seasonality, another logical framing is that habitat structure matters more for nekton assemblages during seasonally high biomass of seagrass-that is, season-specific habitat effects. Seasonality in the degree of habitat provision by seagrass has also been reported for infaunal assemblages (Włodarska-Kowalczuk et al 2014).…”

Functional uniformity underlies the common spatial structure of macrofaunal assemblages in intertidal seagrass beds

“…Comparable data on the taxa comprising each benthic macrofaunal assemblage and on their relative importance were obtained from the datasets underlying recent published work in intertidal Zosterella habitats carried out at equivalent times of the year (Wlodarska‐Kowalczuk et al ., ) and with the same methodology: (1) on Scolt Head Island (within the Scolt Head National Nature Reserve) in the northwestern European North Sea at 53°N01°E (Barnes & Ellwood, ; Barnes, ), (2) at Knysna (within the Garden Route National Park) on the Indian Ocean coast of South Africa at 34°S23°E (Barnes & Ellwood, , ; Barnes, ; Barnes & Barnes, ) and (3) on North Stradbroke Island (within a Habitat Protection Zone of the Moreton Bay Marine Park) Queensland at 27°S153°E (Barnes & Barnes, ; Barnes & Hamylton, ; Barnes, ). All sites are hence enclosed within areas of high conservation status.…”

Molluscan Fauna in Bang Taboon Mangrove Estuary, Inner Gulf of Thailand: Implications for conservation and sustainable use of coastal resources

“…were recorded in the present study as well and found restricted to the mangrove zone. It was known that these species are instantly climb down from the tree trunks or prop roots to the mangrove floor for feeding when the ebb tide starts and again climb up during the high tide [24].…”